Fuse this card with "Fluffal Owl" to summon "Elemental HERO Gaia", then use both the monsters' effects to add back the "Polymerization" you used and another "HERO" you want from your Deck, so that you get 2 of the 3 cards needed for another Fusion Summon.

Send this card from your Deck to the Graveyard using the second effect of "Elemental HERO Blazeman" to add any "HERO" to your hand while also making "Blazeman" a DARK monster (be careful that if you do so, you cannot Summon non-Fusion Monsters with "De-Fusion" that turn).

Send this card to the Graveyard by the effect of "Dark World Dealings", then add any "HERO" you want.

Give this card to your opponent using "Gift Exchange", then if and when it is sent to the Graveyard, you get to use its effect.

You can Summon "Vision HERO Trinity" or "Elemental HERO Core" using three Level 4 "Elemental HEROs", then use "De-Fusion" to Summon the Fusion Materials again. Using "Shadow Mist's" effect, add a Level 4 HERO (preferably "Elemental HERO Bubbleman" due to the fact that you can Special Summon him and it's likely that you won't have any more monsters in hand after Summoning a three-material Fusion Monster). Using these 4 Level 4 monsters, Summon "Number 86: Heroic Champion - Rhongomyniad" (this can also work with only 3 monsters, since its invincibility applies starting at 3 Xyz Materials).